Founded in the 12th century, this was the first Cistercian monastery on the island, and it grew to be the most important. Much of it is gone now, but enough is left to give you an idea of what Mellifont was like in its day, when it was the center of Cistercian faith in Ireland, with more than 400 monks living and working within its walls. You can see the outline of the cross-shaped nave, as well as the remains of the cloister, refectory, and the warming room (the only part of the monastery with heating—after all, monks were supposed to live lives of suffering). Mellifont was closed in the 16th century during Henry VIII’s dissolution of the monasteries, and a manor house was soon built on the site for an English landlord, using the abbey stones. A century later, that house would be the last place where Hugh O’Neill, the final Irish chief, stayed before surrendering to the English and then fleeing to Europe in 1607. At the informative visitor center next door, you can find out more about the monastery and its long complex history.